The present Invention is directed to an improvement in dry cleaning, more specifically a method and pretreatment additive which are capable of both deodorizing and improving the elimination of stains and contaminants from fabric.
Existing dry cleaning systems utilize perchlorethylene or hydrocarbon solvents with elevated flash points. Into these systems various contaminants are introduced. One source of contaminants is body excrements (i.e. perspiration and body oil, generally known as sebaceous soil), primarily comprised of short-chain fatty acids. These fatty acids can contribute to system acidity, odors, and garment staining (swales).
Another contaminant found in the dry cleaning system is moisture. One of the most important ways in which moisture enters the system is as a result of pre-spotting. When there are water soluble stains to be removed, it is customary for operators to use live steam in advance of the dry cleaning process.
Moisture also enters the system from that which is inherently in the fabric (also known as fiber regain), as well as a broad range of pre-spotting detergents and system detergents. All of these may contain water introduced during manufacture.
Fabric stains fall into two principal categories, water soluble stains (usually called xe2x80x9csweetxe2x80x9d stains) and oil soluble stains. The solvent is effective to remove the latter, but not the former. Therefore, the presence of water in the system, if properly utilized, assists in the removal of the sweet stains.
However, the presence of water in the system presents certain problems and, for best results, it is important that a proper balance be maintained. If there is an excess of water, shrinkage, redeposition and the like occur because the known detergents do not hold the water in a complete suspension. In addition, the dry cleaning machines themselves contain elements which will be corroded in the presence of water, especially if the system is acidic. Moreover, it has been found that such corrosion can occur quite rapidly. On the other hand, since the presence of water aids in removing the water soluble stains which the dry cleaning solvent would otherwise leave behind, the aforementioned balance is necessary if the systems are to function at maximum efficiency.
In addition to the foregoing, stabilizers are customarily introduced (especially if perchlorethylene is the solvent) in order to minimize the corrosive effect on the metal surfaces and elements within the dry cleaning machine, as well as any metallic buttons or other ornamentation found on the fabric itself. Most dry cleaning machines are equipped with distillation units which are used throughout the day to constantly purify the solvent. However, this process destroys the original stabilizer, thereby permitting the distilled solvent to become increasingly acidic. When this occurs, the corrosive attack on any metal contacted by the solvent is increased, and malodors are created and become increasingly pervasive throughout the entire system. Thus, washing systems (whether dry or wet) perform best on the alkaline side, e.g. at a pH of at least 7, preferably 7 to 9 xc2xd, most preferably 8.3 to 8.5.
Furthermore, distillation creates yet another problem. It removes coloration, fatty acids, residues, etc.; however, it also removes detergents, whereby the separation of water and the solvent can readily occur. Since the solvents themselves become corrosive when combined with the water at an acid pH, redeposition can occur and undesirable odors can be generated.
In addition to the foregoing, water in the dry cleaning system, if properly dispersed, acts to conduct static electricity to ground. The static is generated by friction occurring within the dry cleaning machine and, if the water is not properly dispersed, an electrical imbalance occurs and the ability to ground the static charge is impaired. The result of the static electricity is linting and poor xe2x80x9cdrapexe2x80x9d of the garments being cleaned.
In order to achieve the proper water-solvent balance, the present Invention provides a pretreatment additive which is introduced into the solvent upstream of the cleaning bath. The additive reduces static electricity which can cause linting, neutralizes solvent acidity to reduce corrosion, odorizes the solvent, and does not adversely affect the filtering and distillation operations. In accordance with the present Invention, the additive contains sodium bicarbonate and an antistatic agent; preferably, an odorant is also included.
The additive of the present Invention advantageously includes at least 90% by weight of sodium bicarbonate and at least 1% by weight of the antistatic agent. For best results, an odorant is present and it preferably consists of at least 1% by weight based on the additive.
The present Invention is used by introducing approximately 3 to 5 ounces of the additive ahead of the dry cleaning bath of a 50 pound capacity machine. The additive is circulated with the solvent throughout the machine system, inclusive of its filters, 4-5 minutes, whereby it reacts with the solvent in the reservoir to provide the aforementioned benefits. The actual dosage may vary depending upon system water content; generally, the above dosage will permit subsequent processing of up to 400 pounds of garments.